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I've removed the ancient handsfree cradle in my 2003 Avensis. It was originally installed by a Toyota garage. I've put a DAB+ adapter where it used to be, and plan to power it using the 12 V DC conductors from the handsfree cable.

Then it struck me: What if some of the other conductors could be converted to AUX IN for the car stereo? (That would be way better than the tiny FM transmitter.)

A picture of the phone component is attached. It's labeled BL4041X 09/04, but it doesn't yield any Google results.

So, the question: Does anyone know if there exists a diagram of the conductors, or even if it is possible to create an AUX IN from this?

component in which one can connect specific phone adaptors


Update: Having had no luck so far (not even getting 12 V current), I finally removed the necessary panels in the cabin, and found that my previous hypothesis was wrong. The other end is some proprietary 15 pin D-sub, and it connects into a box behind the glove compartment.

handsfree controller with inputs

Left to right: the D-sub connenctor, a 2.5 mm jack for the microphone, 4 pin connector (sound?), 4 pin connector (power?)

I think this should simplify my project. Now I can simply remove that box, and just use those standard connectors instead. I'll post an answer as soon as I've been able to complete it. In the meantime, if anyone recognizes those 4 pin cables, I'll be happy to receive a link to a wiring diagram. I suspect it will make everything go a little bit quicker.

  • You need to go to the vehicle wiring diagram to find out if any of those go directly to the stereo / amp or just to a control module... – Solar Mike Jul 4 '18 at 20:50
  • It's was retrofitted, so I'm sort of assuming it's using some standard interface to the radio. However, it's funny how asking a question makes one research it even more. I think I'm looking at the business end of a 12 pin CD changer connector. It has 14 pins in the picture, but I suspect two of those go directly to the extra microphone. (Will edit the question.) – Martin Strand Jul 4 '18 at 21:01
  • That diagram could still tell you a lot... – Solar Mike Jul 4 '18 at 21:02
  • Some obvious things: two connectors on the right are Pos/Neg. The four pins on the left appear to be (if coloring is nominal) for speakers (output). The rest would be for the interface. The "09/04" is the date of manufacture. "BL4041" brings up some stuff on Google, but nothing which helps anything. – Pᴀᴜʟsᴛᴇʀ2 Jul 4 '18 at 21:18
  • @Pᴀᴜʟsᴛᴇʀ2 That's actually quite useful. (I've identified Pos/Neg already). Entering dummy mode: I could succeed if I identified and grouped all R/L connectors, and soldered them to R/L on an AUX connector? If so, then I just need to add GND (neg?) to finish the build? – Martin Strand Jul 4 '18 at 21:26

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